Projectile trap assemblies or backstop assemblies have been known whose object is to slow down and capture projectiles fired into them from a specified distance. The following U.S. patents have disclosed examples of different types of projectile trap assemblies or backstop assemblies: U.S. Pat. No. 5,171,020 issued to Wojcinski; U.S. Pat. No. 5,340,117 issued to Wojcinski; U.S. Pat. No. 5,435,571 issued to Wojcinski et al.; U.S. Pat. No. 5,607,163 issued to Nesler. In these patents, various target backstop assemblies using particulate granulated material are disclosed. The granulate material traps the projectiles. After a period of time of use, the granulate material may be saturated so that the granulate material and the entrapped projectiles or projectile fragments are transferred to be recovered and reconditioned thereafter. The reconditioned granulated material is re-used in the assembly. These types of assemblies may be used for a period of time depending on their trapping capacity. The longer, wider, and thicker the granulated material of the trap assembly is, the larger the capacity of the assembly has, and the less frequent the trap assembly needs to be transferred and recycled. However, the size of the trap assembly does not ultimately determine the trapping capacity. Most of the projectiles are generally trapped in a certain region of the granulated material, which need to be removed and recycled frequently, whereas the projectiles trapped in the other regions of the granulated material do not.
Therefore, a substantial need exists for a trap assembly which is capable of recovering and recycling a designated region of the granulated material of the trap assembly so as to prolong the use of the trap assembly before the entire trap assembly needs to be recycled.